walls from deflecting with the diaphragms. Isolated
(For cantilevered walls, see Paragraph 3 below.) The
partitions will be braced to overhead construction or
design force will be applied to the wall in both
anchored to other isolated cross walls to ensure
inward and outward directions.
lateral stability under out-of-plane loading.
(2)
Wall behavior.
Walls distribute normal
f.
Cast-in-Place Concrete Shear Walls.
forces vertically to the horizontal resisting elements
above or below. They may also distribute normal
(1)
General requirements.
Reinforced
forces to frames, or other walls or frames. A wall
concrete shear walls shall comply with the following
may be either continuous or discontinuous across its
provisions.
supports.
(a)
Seismic Design Categories A and B.
(3) Cantilevered walls. Where walls, such as
Shear walls may be of any type permitted by ACI
parapets, are cantilevered, the anchorage for reaction
318 and FEMA 302.
and cantilever moment is required to be fully
developed (Figure 7-5, part c). Where a parapet wall
(b)
Seismic Design Category C.
Shear
is anchored to a concrete roof slab and is not a
walls may be detailed plain concrete shear walls,
continuation of a wall below, the roof slab will be
ordinary reinforced concrete shear walls, or special
designed for the cantilever moment.
Where the
reinforced concrete shear walls as prescribed in
parapet is a continuation of a wall below, the
Chapter 9 of FEMA 302.
cantilever moment will be divided between the
concrete slab and the wall below in proportion to
(c) Seismic Design Categories D, E, and F.
their relative stiffnesses. Where the parapet is an
Shear walls shall be special reinforced concrete shear
extension of a wall below and is anchored to a roof or
walls in accordance with Section 9.3.2.4 of FEMA
floor of wood, metal deck, or other similar materials,
302.
the moment at the base of the parapet will be
developed into the wall below.
In this case, the
(2) General design criteria. The criteria used
anchorage force to the roof will be determined by the
to design reinforced concrete shear walls will be ACI
usual methods of analysis, assuming a pinned
318 requirements for "structural walls," as modified
condition for the connection of the roof to the wall.
by the provisions given in Chapter 9 of FEMA 302.
For tilt-up and other precast concrete shear walls,
(4) Connections. Walls will be anchored to
refer to Paragraph 7-2g. For details of reinforcement,
the structural frame or diaphragm by dowels, anchor
see Figure 7-6 and 7-7.
bolts, or other approved methods to withstand the
design forces, but in no case less than 200 pounds per
linear foot. Dovetail anchors are inadequate for this
purpose.
Nonstructural partitions will be isolated
from exterior walls and shear partitions so as to
prevent buttress action, which would restrict shear
7-17
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